Movable-lens position control apparatus

ABSTRACT

An optical apparatus having an image-forming optical system comprising a movable lens, comprises a lens drive mechanism for moving the movable lens, a focus adjusting device for automatically adjusting an imaging position by moving the movable lens or another optical element, based on detection of a focus detecting-device, a detecting device for detecting a temperature change or a humidity change, and a control device for actuating the lens drive mechanism upon stop of operation of the focus adjusting device, based on detection in the detecting device, to move the movable lens for correction.

This application is a division of application Ser. No. 08/787,545 filedJan. 22, 1997 now U.S. Pat. No. 6,268,885.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical apparatus having a movinglens.

2. Related Background Art

In the field of the optical apparatus including cameras,compactification of photographing optical system and reduction of imagesize of solid state image sensing device has quickly been advancingthese years. In addition, plastic materials are often used as opticalmaterials for making the photographing optical system. Use of plasticmaterials has such features that a lens can be molded readily by mold,that arbitrariness of shape thereof is high, and that the cost merit ishigher than that of glass materials. Because of such features, lensesmade of plastic materials are frequently used in a viewfinder system, inan infrared active autofocus unit, in parts of the photographing opticalsystem, and so on.

The plastic materials show greater changes of physical propertiesagainst environmental changes than inorganic glass materials. Forexample, PMMA of a plastic material has a large coefficient of linearexpansion: 67.9×10⁻⁶/° C. typical, whereas LaK 14 (available from OHARA)of an inorganic glass has a coefficient of linear expansion one order ofmagnitude smaller than it: 57×10⁻⁷/° C. As for changes of refractiveindex against temperature changes, PMMA shows 1.0 to 1.2×10⁻⁴/° C.typical, whereas the above LaK 14 shows 3.9 to 4.4×10⁻⁶/° C. at theD-line two orders of magnitude smaller than those.

As explained above, the plastic materials show greater changes ofvarious optical constants (the refractive index, the shape, etc.)against temperature changes than the inorganic glass materials. Forexample, the lenses made of the plastic materials, so-called plasticlenses, have greater changes of focal length against temperature changesthan the lenses made of the inorganic glass materials.

Further, the plastic materials have larger water absorption rates thanthe inorganic glass materials. Therefore, the various optical constantsof the plastic lenses change greater against humidity changes, similarlyas against temperature changes, than the lenses made of the inorganicglass materials.

The effects as discussed previously can be attained by using the plasticlens in parts of the optical system. However, it raises the problem thatthe optical properties including the focal length change greater againstenvironmental changes, particularly against temperature changes oragainst humidity changes, than in the case of use of the lenses made ofthe inorganic glass materials.

The recent optical apparatus is compactified by compactifying thephotographing optical system, compactifying the solid state imagesensing device, and increasing the density of various elements. Thisraises the problem that the temperature changes, moisture changes, orthe like increase an effect of deviation of the image plane of theoptical system used in the optical apparatus with respect to theintended image plane. It is, therefore, a significant issue how toeffectively correct the deviation of the imaging position due to suchenvironmental changes.

Further, many recent optical devices are provided with an autofocusingfunction (AF function) for automatically detecting the in-focus positionof optical system. During photography with operation of the AF function,for example, if any obstacle such as a car or a pedestrian goes betweenthe optical apparatus and the object, the AF means will make the opticalsystem in focus with the obstacle. This will result in failing to imagethe target object on the image plane. Thus, there was the problem thatphotography must be made under stop of the AF function in order to avoidit. Stop of the operation of the AF function during photography is notpreferred, because the position of the image plane changes greatly withthe environmental changes as discussed previously in the case of theoptical apparatus using the optical system including the plastic lens.

SUMMARY OF THE INVENTION

One aspect of the invention is to provide an optical apparatus arrangedto detect temperature or/and humidity and to effect correction ofposition based on a detection result thereof when a moving lens is at astop of operation.

The other aspects will become apparent from the detailed descriptionthat follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic drawing to show the principal part of Embodiment 1according to the present invention;

FIG. 2 is a flowchart to show the operation of Embodiment 1 according tothe present invention;

FIG. 3 is a schematic drawing to show the principal part of Embodiment 2according to the present invention;

FIG. 4 is a flowchart to show the operation of Embodiment 2 according tothe present invention;

FIG. 5 is a schematic drawing to show the principal part of Embodiment 3according to the present invention;

FIG. 6 is a flowchart to show the operation of Embodiment 3 according tothe present invention;

FIG. 7 is a flowchart to show the operation of the optical apparatus asthe fourth embodiment;

FIG. 8 is a flowchart to show the operation of the optical apparatus asthe fifth embodiment;

FIG. 9 is a flowchart to show the operation of the optical apparatus asthe sixth embodiment;

FIG. 10 is a cross-sectional view of the principal part to show theseventh embodiment of the optical apparatus according to the presentinvention;

FIG. 11 is a flowchart to show the operation of the optical apparatusshown in FIG. 10;

FIG. 12 is a cross-sectional view of the principal part to show theeighth embodiment of the optical apparatus according to the presentinvention;

FIG. 13 is a flowchart to show the operation of the optical apparatusshown in FIG. 12;

FIG. 14 is a cross-sectional view of the principal part to show theninth embodiment of the optical apparatus according to the presentinvention; and

FIG. 15 is a flowchart to show the operation of the optical apparatusshown in FIG. 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram to show the principal part of Embodiment 1 ofthe present invention. In the figure numeral 1 denotes an optical system(a photographing system), which is a rear focus zoom lens (hereinafterreferred to as “RFZ” lens) of the so-called four-unit configurationcomposed of four lens units.

The RFZ lens 1 is comprised of a first lens unit (hereinafter referredto as “front lens”) 101 being a fixed lens unit, a second lens unit(hereinafter referred to as “variator”) 102 with a magnification changeor zoom function being a moving lens unit, a third lens unit(hereinafter referred to as “afocal”) 103 being a fixed lens unit, and afourth lens unit (hereinafter referred to as “RR”) 104 being a movinglens unit and having a function as a compensator for compensating forvariations in image plane due to focus and magnification changes.

Practically, the above lens units are composed of a plurality of lenses.For example, in the present embodiment, the front lens 101 is comprisedof three lenses, the variator 102 of three lenses, the afocal 103 of asingle lens, and the RR (rear relay) 104 of two lenses, thusconstituting the four-unit and 9-lens configuration.

In the present embodiment, a plastic lens made of a plastic material isused in at least one lens unit out of the lens units. The material forthe plastic lens may be selected from acrylic based plastics, polyolefinbased plastics, polycarbonate, and so on.

There is no specific limitation on where the plastic lens should be usedin the lens units in the present embodiment, and there are some caseswithout using the plastic lens in the lens units at all.

Numeral 2 designates a photoelectric conversion element (image pickupmeans) such as a CCD, and 3 an aperture member for adjusting a quantityof light incident to the photoelectric conversion element 2. Numeral 6is an aperture driver, which is comprised of an iG meter or a STEP motoror the like and which changes the area of the aperture of the aperturemember 3 by driving aperture wings in the aperture member 3 nearlyperpendicularly to the optic axis, based on a signal from a controller7, so as to keep the quantity of light incident to the photoelectricconversion element 2 constant. Numeral 4 designates an aperture positiondetector, which detects the size of the aperture of the aperture member3. Numeral 5 represents a detection circuit for converting a detectionsignal from the aperture position detector 4 to a signal processable bythe controller 7 and outputting the obtained signal.

Numerals 8, 9 are driving units such as step motors for driving themoving lens units 102, 104, respectively, and numerals 10, 11 aredrivers for driving the driving units 8, 9, respectively. Numeral 12stands for a temperature detector such as a thermistor or thermallysensitive resistor, and numeral 13 for a detection circuit for detectingan output from the temperature detector 12 and outputting a signal tothe controller 7. For detecting humidity, the element 12 serves as ahumidity detector such as an electrostatic capacity type sensor or athermistor.

Numeral 14 denotes an amplifier for amplifying an output from thephotoelectric conversion element 2, 15 a process circuit for convertinga signal from the amplifier 14 to a signal such as an NTSC video signal,16 an autofocusing device for generating a signal for autofocusing(hereinafter referred to as AF) from a signal output from the processcircuit 15 and effecting the AF operation, and 17 an AF controllercomprised of a switch for turning the AF operation of AF device 16 on oroff. An example of the method of AF is the so-called hill climbingmethod, for example, the method as proposed in U.S. Pat. No. 4,804,831.

In the present embodiment, the controller 7 obtains a drive amount of RR104, based on an in-focus signal from the AF device 16, and supplies itto the driver 11. Then the driver 11 drives the motor 9, based on thein-focus signal, to move the RR 104, thereby effecting AF.

The present embodiment employs the plastic lens in at least one lensunit. Therefore, a temperature change or a humidity change around theplastic lens due to an environmental change will change the shape of theplastic lens as described previously and change the refractive indexthereof because of a large temperature coefficient of refractive indexof the material, thereby greatly changing the focal length. Thefollowing description mainly concerns the temperature changes as theenvironmental changes, but it is noted that the same can be applied tothe humidity changes.

The temperature changes will change focal lengths of the respective lensunits, which will also change the total focal length of the lens system1. As a result, the image plane will deviate from the image plane atreference temperature (which is set at 20° C. in the presentembodiment). Namely, defocus occurs.

Accordingly, when photography is carried out in fixed focus withoutaction of the AF function, defocus occurs with changes of temperature,which is a problem very undesirable for the optical apparatus. In orderto solve this problem, the present embodiment is thus arranged to detectthe temperature and correct the focus in accordance with a temperaturechange.

Specifically, even if an environmental change (a temperature change or ahumidity change) occurs while the AF controller 17 stops the operationof the AF device 16 (or stops the drive unit 9), the controller 7 drivesthe motor 9 through the driver 11, based on the output signal from thedetection circuit 13, to move the RR (moving lens) 104. This effectscorrection for the position of the image plane, thereby achieving a goodimage.

The controller 7 has data of focus moving amount per unit temperature(temperature correction coefficient data) Trr. Then, the focus movingamount data Trr is multiplied by a temperature change amount ΔT toobtain a focus moving amount or correction amount data(temperature-corrected position data) Prr.

ΔT=|detected temperature−reference temperature|Prr=ΔT×Trr

Here, the temperature correction coefficient data is defined as afunction of position of the moving lens unit for magnification change.The above equations can be applied to humidity as they are.

The operation of the present embodiment is next explained using theflowchart of FIG. 2.

In FIG. 2, it is determined at step 201 whether the AF function of theAF device 16 is on or off. If it is on then an AF off flag is cleared atstep 202 and the flow returns to step 201. If it is off then it isdetermined at step 203 whether the AF off flag is cleared. If cleared,the detection circuit 13 reads a temperature detection output at step204, the detected temperature is set as a reference temperature at step205, and the AF off flag is set at step 206. If the AF off flag is setat step 203, the detection circuit 13 reads a temperature detectionoutput at step 207 and it is determined at step 208 whether the detectedtemperature is equal to the reference temperature. If they are equal,the flow returns to step 201. If they are different, the temperaturechange amount ΔT and correction amount Prr are calculated to perform thetemperature compensation control for driving the RR 104 at step 209, andthe temperature detected at step 210 is set as a reference temperature.Then the flow returns to step 201.

As described above, the present embodiment is arranged to obtain goodimage information in such a way that when the operation of the AF device16 is stopped and if there is an environmental change, the controller 7drives RR 104, based on the signal from the detection circuit 13,thereby maintaining the in-focus state.

FIG. 3 and FIG. 4 are a schematic drawing of the principal part and theflowchart of the operation of Embodiment 2 according to the presentinvention. In the drawing the same elements as those shown in Embodiment1 of FIG. 1 are denoted by the same reference numerals.

In the drawing, numerals 18, 19 denote switches for manual focus controldevice (hereinafter referred to as MFD). With either switch kept in theon state, the switch 18 drives the focus lens 104 to the nearest extremeor the switch 19 drives it to the infinite extreme. The presentembodiment is based on the premise of recognition that the focusposition at the end of the MFD operation is the in-focus position andthat the temperature at the end of the operation is the referencetemperature. Therefore, the present embodiment is different fromEmbodiment 1 only in that when the manual focus control is carried out,the temperature at the end of operation is stored and, based thereon, atemperature change is detected and correction is made, and the otherarrangement of the present embodiment is the same as that of Embodiment1.

The operation of the present embodiment is next explained using theflowchart of FIG. 4.

It is determined at step 401 whether the MFD switch 18 or 19 is on oroff. If either one is on, an MFD off flag is cleared at step 402 andthen the flow returns to step 401. If they are off, it is determined atstep 403 whether the MFD off flag is cleared. If cleared, thetemperature detection output is read at step 404, the detectedtemperature is set as a reference temperature at step 405, and the MFDoff flag is set at step 406. If the MFD off flag is set at step 403, thetemperature detection output is read at step 407 and it is determined atstep 408 whether the detected temperature is equal to the referencetemperature. If they are equal, the flow returns to step 401. If theyare different, the temperature change amount ΔT and correction amountPrr are calculated to perform the temperature compensation control fordriving RR 104 at step 409, the temperature detected is set as areference temperature at step 410, and then the flow returns to step401. In the MFD, any means that can detect the operation thereof may beemployed without having to be limited to on/off of switch as described.

FIG. 5 and FIG. 6 are a schematic drawing of the principal part and aflowchart of the operation of Embodiment 3 according to the presentinvention. In the drawing the same elements as those shown in Embodiment1 of FIG. 1 are denoted by the same reference numerals.

In the drawing, numerals 20, 21 designate zoom switches. With eitherswitch kept in the on state, the zoom switch 20 drives the variator lens103 to the telephoto extreme or the zoom switch 21 to the wide angleextreme. The present embodiment is different from Embodiment 1 in thatwhen the view angle is changed by the zoom operation, it is determinedthat an idle state is broken, the temperature at the end of zoomoperation is stored, a temperature change is detected as assuming thatthe idle state is again established after that, and correction is madebased thereon, and the other arrangement of the present embodiment isthe same as that of Embodiment 1.

The operation of the present embodiment is next described using theflowchart of FIG. 6.

It is determined at step 601 whether the zoom switch 20 or 21 is on oroff. If either one is on, a zoom off flag is cleared at step 602 and theflow returns to step 601. If they are off, it is determined at step 603whether the zoom off flag is cleared. If cleared, the temperaturedetection output is read at step 604, the detected temperature is set asa reference temperature at step 605, and the zoom off flag is set atstep 606. If the zoom off flag is set at step 603, the temperaturedetection output is read at step 607 and it is determined at step 608whether the detected temperature is equal to the reference temperature.If they are equal, the flow returns to step 601. If they are different,the temperature change amount ΔT and correction amount Prr arecalculated to perform the temperature compensation control for drivingRR 104 at step 609, the detected temperature is set as a referencetemperature at step 610, and then the flow returns to step 601. In thepresent embodiment, the detection of zoom operation may be done by anymeans that can detect the operation without having to be limited toon/off of switch as described.

As explained above, employment of the configuration of the presentembodiment permits good images without defocus to be obtained even withtemperature changes during zooming, during the operation of the AFfunction, or during stop of the AF function, or even with occurrence ofdeviation from the reference temperature though the temperature has beenkept constant.

The present embodiment uses a single temperature detector 12, but it maybe modified to use plural detectors, which can achieve better effects.

The present embodiment was described as an example where theenvironmental changes were the temperature changes, but with humiditychanges or pressure changes as environmental changes, the configurationas described above can handle such changes in the same manner as long asthe apparatus is provided with a means for detecting such changes. Forexample, the apparatus may be provided with either a temperaturedetector or a humidity detector, or the apparatus may be provided withthe both detectors and arranged to correct defocus due to thetemperature changes and humidity changes.

The embodiments as described above can achieve the optical apparatussuitable for video cameras, silver-salt cameras, electronic stillcameras, and so on in such an arrangement that while photography is madewith operating the autofocusing function using the optical system(photographing lens) having a moving lens unit to move on the opticalaxis in order to achieve focus or magnification change, even if there isan environmental change upon stop of the operation of the autofocusingfunction for some reason, for example, if there is a temperature changeor a humidity change, deviation of the image plane can be corrected forby properly setting movement of the moving lens unit, when necessary,according to the environmental change, whereby high optical performancecan be maintained.

The fourth embodiment is next described using FIG. 7.

Since the structure itself of the optical apparatus of the fourthembodiment is the same as in FIG. 1, description of the components isomitted herein.

In the fourth embodiment the controller 7 obtains a drive amount of RR104, based on the in-focus signal from the AF device 16, and outputs adrive control signal to the driver 11. Then the driver 11 drives thelens drive unit 9, based on the drive control signal from the controller7, to move RR 104 along the direction of the optical axis, therebyeffecting AF of RR 104.

Since the optical system 1 of the fourth embodiment employs the plasticlens in at least one lens unit, as discussed previously, occurrence of atemperature change or a humidity change around the plastic lens due toan environmental change will change the shape of the plastic lens andchange the refractive index because of the large temperature coefficientof refractive index of the material, as described previously, so as togreatly change the focal length, which inevitably changes the totalfocal length of the optical system 1. Because of it, if photography iscarried out in fixed focus without action of the AF function, theposition of the image plane will deviate from that at the referencetemperature (for example, 20° C.) with temperature changes, which willcause so-called defocus and which will degrade the optical performanceas an optical apparatus for clear photography of object.

In order to cancel the defocus occurring with environmental changesduring photography under stop of the AF function and in fixed focus, thefourth embodiment is arranged so that when the AF controller 17 stops(or turns off) the operation (function) of the AF device 16, thedetector 12 detects the ambient temperature of the optical system 1, thetemperature is stored, and thereafter, if the ambient temperaturechanges, the function of the AF device 16 is utilized to move the RR 104to the in-focus position, thereby correcting deviation in the positionof the image plane of the optical system due to the change of theambient temperature.

The following description will concern the deviation of the image plane(defocus) and solving methods of the deviation of the image plane,mainly focusing on the temperature changes as environment changes, butthe same solving methods can be applied to the cases where defocusoccurs from problems due to the humidity changes.

Specifically describing the correction for variations in the position ofthe image plane of the optical system in the fourth embodiment, thecontroller 7 sets the detected temperature obtained from the detector 12as a reference temperature when the AF controller 17 stops (or turnsoff) the operation (function) of the AF device 16, and a determiningcircuit not shown determines whether the detected temperature obtainedfrom the above detector 12 after setting of the reference temperaturehas a change. If the later detected temperature as a determinationobject shows a change, the AF device 16 is functioned to control thedrive of the lens drive unit 9, based on the in-focus signal of the AFdevice 16, to move RR 104 to the in-focus position, thereby correctingvariation in the position of the image plane of the optical system dueto the change of ambient temperature. This can correct the variation inthe position of the image plane of the optical system due to the changeof ambient temperature, thereby obtaining good image information.

The operation of the fourth embodiment is next explained using theflowchart of FIG. 7. It is determined at step 1201 whether the AFfunction of the AF device 16 is on or off. If it is on, the AF off flagis cleared at step 1202 and then the flow returns to step 1201. If theAF function is off, it is determined at step 1203 whether the AF offflag is cleared. If it is cleared, the detector 12 reads a temperaturedetection value at step 1204, the temperature detection value (detectedtemperature) is set as a reference temperature at step 1205, and the AFoff flag is set at step 1206.

If at step 1203 the AF off flag is not cleared, i.e., if it is set, thedetector 12 reads a temperature detection value at step 1207 and it isdetermined at step 1208 whether the temperature detection value(detected temperature) is equal to the reference temperature. If theyare equal, the flow returns to step 1201. If they are different, theflow goes to step 1209 to perform temperature compensated AF control tomove RR 104 to the in-focus position by the AF function, the referencetemperature is updated at step 1210 so that the above detectedtemperature which was the determination object with respect to the abovereference temperature is set as a new reference temperature, and thenthe flow returns to step 1201.

As described above, the fourth embodiment is arranged in such a mannerthat when the AF controller 17 stops the operation of the AF device 16,the detected temperature obtained from the detector 12 is set as areference temperature and that if the detected temperature obtained fromthe detector 12 varies from the reference temperature, the controllerperforms the temperature compensated AF control for moving the RR 104 tothe in-focus position utilizing the function of the AF device 16,thereby achieving good image information.

The optical apparatus of the fifth embodiment shown in FIG. 8 isprovided with the manual focus adjusting devices 18, 19 for manuallydriving the lens drive unit 9 through the controller 7 to move RR 104,thereby effecting manual focusing operation, and thus has the samearrangement as the optical apparatus of the second embodiment. Since theconfiguration of the present embodiment is the same as that of FIG. 3,description of the individual components is omitted herein.

The fifth embodiment is based on the premise that the focus position atthe end of the MFD operation is the in-focus position and that theambient temperature at the end of the operation of RR 104 is set as areference temperature. Namely, when the manual focus adjustment iscarried out during stop of the operation of the AF device 16 by the AFcontroller 17, the ambient temperature is stored during stop of theoperation of RR 104 or at the end of the operation of RR 104. When theambient temperature of the optical system 1 changes after that, thefunction of the AF device 16 is utilized to move RR 104 to the in-focusposition, thereby correcting variation in the position of the imageplane of the optical system due to the change of environmentinformation.

Specifically, the controller 7 sets the detected temperature obtainedfrom the detector 12 as a reference temperature during stop of theoperation of the AF device 16 by the AF controller 17 and upon stop ofthe operation of RR 104 by the manual focusing switch 18, 19 or at thetime of end of the operation of RR 104 by the manual focusing switch 18,19, and a determining circuit not shown determines whether the detectedtemperature obtained from the above detector 12 after setting of thereference temperature has a change. When the later detected temperatureas a determination object has a change, the AF device 16 is functionedto control the drive of the lens drive unit 9, based on the in-focussignal of the AF device 16, to move RR 104 to the in-focus position,thereby correcting the variation in the position of the image plane ofthe optical system due to the change of ambient temperature. This cancorrect the variation in the position of the image plane of the opticalsystem due to the change of ambient temperature, thereby obtaining goodimage information.

The operation of the fifth embodiment is next explained using theflowchart of FIG. 8. It is determined at step 1401 whether the AFfunction of the AF device 16 is on or off. If it is on, the AF off flagis cleared at step 1402 and the flow returns to step 1401. If the AFfunction is off, it is determined at step 1403 whether the MFD switch 18or 19 is on. If either one is on, the MFD off flag is cleared at step1404 and the flow returns to step 1401. If they are off, it isdetermined at step 1405 whether the MFD off flag is cleared. If cleared,a temperature detection value is read at step 1406, the temperaturedetection value (detected temperature) is set as a reference temperatureat step 1407, and the MFD off flag is set at step 1408.

If at step 1405 the MFD off flag is not cleared, i.e., if it is set, atemperature detection value is read at step 1409 and it is determined atstep 1410 whether the temperature detection value (detected temperature)is equal to the reference temperature. If they are equal, the flowreturns to step 1401. If they are different, step 1411 is carried out toperform the temperature compensated AF control for moving RR 104 to thein-focus position by the AF function, and then step 1412 is carried outto update the reference temperature by setting the above detectedtemperature, which was the determination object with respect to theabove reference temperature, as a new reference temperature. Then theflow returns to step 1401.

As described above, the fifth embodiment is arranged in such a way thatin the stop state of the operation of the AF device 16 by the AFcontroller 17 and upon stop of the operation of RR 104 by the manualfocusing switch 18, 19 or at the time of end of the operation of RR 104,the detected temperature obtained from the detector 12 is set as areference temperature and that when the detected temperature obtainedfrom the detector 12 changes relative to the reference temperature, thefunction of the AF device 16 is utilized to move RR 104 to the in-focusposition so as to effect the temperature compensated AF control, therebyobtaining good image information.

The manual focusing devices 18, 19 may be any means that can detect theoperation such as on/off without having to be limited to on/off of theswitches described above.

The optical apparatus of the sixth embodiment shown in FIG. 9 isarranged to have the manual zooming devices 20, 21 for manuallyachieving drive of the lens drive unit 8 through the controller 7 toeffect zooming of the variator lens 102, and thus has the samearrangement as the optical apparatus of the third embodiment. Since theconfiguration of the present embodiment is the same as that of FIG. 5,description of the individual components is omitted herein.

The sixth embodiment is arranged so that in the stop state of theoperation of the AF device 16 by the AF controller 17 and when the viewangle is changed by the zooming operation through the manual zoomingswitch 20, 21, it is determined that the idle state for photographyafter idle is broken, the ambient temperature is stored at the end ofthe zooming operation by the manual zooming switch 20, 21, it is assumedthereafter that the idle state is again established, and when theambient temperature of the optical system 1 changes in such an idlestate, the function of the AF device 16 is utilized to move RR 104 tothe in-focus position, thereby correcting the variation in the positionof the image plane of the optical system due to the change of ambienttemperature.

Specifically, in the stop state of the operation of the AF device 16 bythe AF controller 17 and upon completion of the zooming operation of thevariator lens 102 by the manual zooming device 20, 21, the controller 7sets the detected temperature obtained from the detector 12 as areference temperature, and a determining circuit not shown determineswhether a detected temperature obtained from the above detector 12 aftersetting of the reference temperature has a change. When the laterdetected temperature as a determination object has a change, the AFdevice 16 is functioned to control the drive of the lens drive unit 9,based on the in-focus signal from the AF device 16 so as to move RR 104to the in-focus position, thereby correcting the variation in theposition of the image plane of the optical system due to the change ofambient temperature. This can correct the variation in the position ofthe image plane of the optical system due to the change of ambienttemperature, thereby obtaining good image information.

The operation of the sixth embodiment is next explained using theflowchart of FIG. 9. It is determined at step 1601 whether the AFfunction of the AF device 16 is on or off. If it is on, the AF off flagis cleared at step 1602 and the flow returns to step 1601. If the AFfunction is off, it is determined at step 1603 whether the zoom switch20 or 21 is on or off. If either one is on, the zoom off flag is clearedat step 1604 and then the flow returns to 1601. If they are off, it isdetermined at step 1605 whether the zoom off flag is cleared. If it iscleared, a temperature detection value is read at step 1606, thetemperature detection value (detected temperature) is set as a referencetemperature at step 1607, and the zoom off flag is set at step 1608.

If at step 1605 the zoom off flag is not cleared, that is, if it is set,a temperature detection value is read at step 1609, and it is determinedat step 1610 whether the temperature detection value (detectedtemperature) is equal to the reference temperature. If they are equal,the flow returns to step 1601. If they are different, step 1611 iscarried out to effect the temperature compensated AF control for movingRR 104 to the in-focus position by the AF function and then step 1612 iscarried out to set the above detected temperature as a referencetemperature. Then the flow returns to step 1601.

As described above, the sixth embodiment is arranged in such a way thatin the stop state of the operation of the AF device 16 by the AFcontroller 17 and at the end of the zooming operation by the manualzooming device 20, 21, the detected temperature obtained from thedetector 12 is set as a reference temperature and that when the detectedtemperature obtained from the detector 12 changes with respect to thereference temperature, the function of the AF device 16 is utilized tomove RR 104 to the in-focus position so as to effect the temperaturecompensated AF control, thereby obtaining good image information.

The manual zooming devices 20, 21 may be any means that can detect theoperation such as on/off, without having to be limited to on/off of theswitches described above.

The optical apparatus of the seventh embodiment shown in FIG. 10 andFIG. 11 is constructed in the same structure as the optical apparatus ofthe first embodiment except for the controller 7′. In more detail, theoptical apparatus of the seventh embodiment is provided with such atemperature compensated control function that a memory portion (memorymeans) not shown of the controller 7′ for controlling the whole of theoptical apparatus stores position data of the moving lens unit (RR lens)104 at a reference temperature TO (reference ambient temperature) (whichis set at 20° C. in the seventh embodiment) described hereinafter, andcontrol information including plural temperature compensationcoefficient data Trr per unit temperature for correcting this positiondata based on an ambient temperature (detected temperature) from thedetector 12, that the above temperature correction coefficient data Trris multiplied by a temperature change value ΔT, which is an absolutevalue of a difference between the detected temperature from the detector12 and the above reference temperature, to obtain correction amount data(temperature corrected position data) Prr for correction for variationsin the position of the image plane due to changes of ambient temperatureof the optical system, and that the lens drive unit 9 moves RR 104 alongthe direction of the optical axis by this correction amount Prr.

The following equations represent the relation among the temperaturechange value ΔT, focus movement amount Trr, and correction amount Prr insuch a temperature compensated control function.

ΔT=|detected temperature−reference ambient temperature|Prr=ΔT×Trr

Here, the temperature correction coefficient data Trr is defined as afunction of position of the moving lens unit for magnification change.The above equations can be applied to humidity changes as they are.

In the seventh embodiment, when the operation (function) of the AFdevice 16 is stopped (or turned off) by the AF controller 17, theambient temperature of the optical system 1 is detected by the detector12 and then is stored, and it is determined whether a temperature changevalue ΔT of a difference between a latest detected temperature obtainedfrom the detector 12 after the foregoing ambient temperature and thereference temperature is more than a predetermined, specific value Ktdescribed hereinafter. If the temperature change value ΔT is not morethan the specific value Kt, the correction amount (temperature correctedposition data) Prr is obtained from the above relation, and the lensdrive unit 9 moves RR 104 to correct variation in the position of theimage plane of the optical system due to the change of ambienttemperature. On the other hand, if the above temperature change value ΔTis more than the specific value Kt, the above function of the AF device16 is utilized to move RR 104 to the in-focus position, therebycorrecting the variation in the position of the image plane of theoptical system due to the change of ambient temperature.

Specifically, the controller 7′ stores the detected temperature obtainedfrom the detector 12 when the operation (function) of the AF means 16 isstopped (or turned off) by the AF controller 17. Then the controller 7′calculates the temperature change value ΔT of the difference between thelatest detected temperature obtained from the detector 12 after thepreviously detected temperature and the reference temperature anddetermines whether the absolute value of this temperature change valueΔT is more than the predetermined, specific value Kt. If the absolutevalue of the temperature change value ΔT is not more than thepredetermined, specific value Kt, the controller obtains the correctionamount (temperature corrected position data) Prr from the foregoingrelation and moves RR 104 by the lens drive unit 9, based thereon,thereby correcting the variation in the position of the image plane ofthe optical system due to the change of ambient temperature. On theother hand, if the absolute value of the temperature change value ΔT ismore than the specific value Kt, the above AF device 16, is functionedto control the drive of the lens drive unit 9, based on the in-focussignal of the AF device 16, to move RR 104 to the in-focus position,thereby correcting the variation in the position of the image plane ofthe optical system due to the change of ambient temperature. This cancorrect the variation in the position of the image plane of the opticalsystem due to the change of ambient temperature, thereby obtaining goodimage information.

The operation of the seventh embodiment is next explained using theflowchart of FIG. 11. It is determined at step 1201′ whether the AFfunction of the AF device 16 is on or off. If it is on, the AF off flagis cleared at step 1202′ and then the flow returns to step 1201′. If theAF function is off, it is determined at step 1203′ whether the AF offflag is cleared. If cleared, the temperature detection value is read bythe detector 12 at step 1204′, the temperature detection value (detectedtemperature) is set as a detected temperature T1 in the MF (manualfocus) mode at step 1205′, and then the AF off flag is set at step1206′.

If at step 1203′ the AF off flag is not cleared, that is, if it is set,a temperature detection value is read by the detector 12 at step 1207′,and it is determined at step 1208′ whether the temperature detectionvalue (detected temperature) is equal to the previous detectedtemperature T1. If they are equal, the flow returns to step 1201′. Ifthey are different, step 1209′ is carried out to obtain a temperaturechange value ΔT of a difference between the later detected temperatureobtained at step 1207′ and the reference temperature T0 and to determineif the absolute value thereof is more than the predetermined, specificvalue Kt. If the temperature change value ΔT is not more than thespecific value Kt, step 1210′ is carried out to obtain the correctionamount Prr from the above relation and to move RR 104, thereby effectingthe temperature compensated control for correcting the variation in theposition of the image plane of the optical system. On the other hand, ifat step 1209′ the absolute value of the temperature change value ΔT ismore than the specific value Kt, step 1211′ is carried out to executethe temperature compensated AF control to move RR 104 to the in-focusposition by the AF function. Then step 1212′ is carried out to updatethe previously detected temperature T1 to the later detectedtemperature. Then the flow returns to step 1201′.

As described above, the seventh embodiment is arranged in such a waythat when the operation of the AF device 16 is stopped by the AFcontroller 17′ and if the temperature change value ΔT of the differencebetween the latest detected temperature obtained from the detector 12and the reference temperature is not more than the predetermined,specific value Kt, the controller executes the temperature compensatedcontrol to obtain the correction amount Prr of RR 104, to move RR 104 bythe lens drive unit 9, and to correct the variation in the position ofthe image plane of the optical system and that, on the other hand, ifthe absolute value of the temperature change value ΔT is more than thespecific value Kt, the controller executes the temperature compensatedAF control to move RR 104 to the in-focus position utilizing thefunction of the AF device 16, thereby achieving good image information.

There is no specific limitation on the reference temperature T0 in theseventh embodiment. For example, it may be a temperature upon executionof lens adjustment or a reference value being an absolute value of adesired temperature. It is, however, preferred to determine thereference temperature at an approximate value to ambient temperatures atwhich the optical apparatus is actually used, because it causes littleerror in arithmetic processing.

The specific value Kt for determining whether the AF function is to beactuated may be determined arbitrarily depending upon opticalcharacteristics of the optical system, material characteristics,specifications of the optical apparatus, and so on. In addition, thespecific value may be arranged to be stored in a rewritable memory unitso as to be changed any time with necessity.

The optical apparatus of the eighth embodiment shown in FIG. 12 and FIG.13 is constructed in the same structure as the optical apparatus of theseventh embodiment except for provision of the manual focusing devices18′, 19′ for focusing RR 104 by manually driving the lens drive unit 9through the controller 7′.

In FIG. 12, numerals 18′, 19′ denote switches for manual focusadjustment (hereinafter referred to as MFD). With either switch kept inthe on state, the switch 18′ drives RR 104 to the nearest extreme or theswitch 19′ drives RR 104 to the infinite extreme.

The eighth embodiment is based on the premise that the focus position atthe end of the MFD operation is the in-focus position and that theambient temperature at the end 6f the operation of RR 104 is detected asa reference temperature. In more detail, while the operation of the AFdevice 16 is stopped by the AF controller 17′ and when the manualfocusing is carried out, the controller stores an ambient temperatureupon stop of the operation of RR 104 or at the end of the operation ofRR 104 and then determines whether a temperature change value ΔT of adifference between a latest detected temperature obtained from thedetector 12 after the ambient temperature and the reference temperatureis more than a predetermined, specific value Kt described below. If thetemperature change value ΔT is not more than the predetermined, specificvalue Kt, the controller obtains the correction value (temperaturecorrected position data) Prr from the above relation and to move RR 104by the lens drive unit 9, thereby correcting the variation in theposition of the image plane of the optical system due to the change ofambient temperature. On the other hand, if the above temperature changevalue ΔT is more than the specific value Kt, the controller moves RR 104to the in-focus position utilizing the function of the above AF device16, thereby correcting the variation in the position of the image planeof the optical system due to the change of ambient temperature.

Specifically, while the operation of the AF device 16 is stopped by theAF controller 17′ and upon stop of the operation of RR 104 by the manualfocusing switch 18′, 19′ or at the time of end of operation of RR 104 bythe manual focusing switch 18′, 19′, the controller 7′ stores thedetected temperature obtained from the detector 12 and calculates thetemperature change value ΔT of the difference between the latestdetected temperature obtained from the detector 12 after the previouslydetected temperature and the reference temperature, and a determiningcircuit not shown determines whether the absolute value of thistemperature change value ΔT is more than the predetermined, specificvalue Kt. If the absolute value of the temperature change value ΔT isnot more than the predetermined, specific value Kt, the controllerobtains the correction amount (temperature corrected position data) Prrfrom the foregoing relation and to move RR 104 by the lens drive unit 9,thereby correcting the variation in the position of the image plane ofthe optical system due to the change of ambient temperature. On theother hand, if the absolute value of the temperature change value ΔT ismore than the specific value Kt, the above AF device 16 is functioned tocontrol the drive of the lens drive unit 9, based on the in-focus signalof the AF device 16, to move RR 104 to the in-focus position, therebycorrecting the variation in the position of the image plane of theoptical system due to the change of ambient temperature. This cancompensate for the variation in the position of the image plane of theoptical system due to the change of ambient temperature, therebyattaining good image information.

The operation of the eighth embodiment is next explained using theflowchart of FIG. 13. It is determined at step 1401′ whether the AFfunction of the AF device 16 is on or off. If it is on, the AF off flagis cleared at step 1402′ and then the flow returns to step 1401′. If theAF function is off, it is determined at step 1403′ if the AF off flag iscleared. If cleared, step 1404′ is carried out to read a temperaturedetection value by the detector 12 and then step 14051 is carried out toset the temperature detection value (detected temperature) as a detectedtemperature T1 in the MF (manual focus) mode. Then step 1206′ is carriedout to set the AF off flag.

If at step 1403′ the AF off flag is not cleared, that is, if it is set,it is determined at step 1407′ whether the switch 18′ or 19′ of MFD ison or off at step 1407′. If either one is on, the MFD off flag iscleared at step 1408′ and then the flow returns to step 1401′. If theyare off, it is determined at step 1409′ whether the MFD off flag iscleared. If it is cleared, the MFD off flag is set at step 1410′, atemperature detection value is read at step 1404′, and the processesincluding step 1405′ and the subsequent processes are carried out.

If at step 1409′ the MFD off flag is not cleared, that is, if it is set,a temperature detection value is read at step 1411′ and it is determinedat step 1412′ whether the temperature detection value (detectedtemperature) is equal to the previously detected temperature T1. If theyare equal, the flow returns to step 1401′. If they are different, step1413′ is carried out to obtain the temperature change value ΔT of thedifference between the later detected temperature obtained at step 1411′and the reference temperature T0 and to determine if the absolute valuethereof is more than the predetermined, specific value Kt. If thetemperature change value ΔT is not more than the specific value Kt, step1414′ is carried out to execute the temperature compensated control toobtain the correction amount Prr from the foregoing relation and to moveRR 104, thereby correcting the variation in the position of the imageplane of the optical system. On the other hand, if at step 1413′ theabsolute value of the temperature change value ΔT is more than thespecific value Kt, step 1415′ is carried out to execute the temperaturecompensated AF control to move RR 104 to the in-focus position by the AFfunction and then step 1416′ is carried out to update the previouslydetected temperature T1 to the later detected temperature. Then the flowreturns to step 1401′.

As described above, the eighth embodiment is arranged in such a way thatwhile the operation of the AF device 16 is stopped by the AF controller17′ and upon stop of the operation of RR 104 by the manual focusingswitch 18′, 19′ or at the end of the operation of RR 104, if thetemperature change value ΔT of the difference between the latestdetected temperature obtained from the detector 12 and the referencetemperature is not more than the predetermined, specific value Kt, thecontroller executes the temperature compensated control to obtain thecorrection amount Prr of RR 104 and move RR 104 by the lens drive unit 9so as to compensate for the variation in the position of the image planeof the optical system and that, on the other hand, if the absolute valueof the temperature change value ΔT is more than the specific value Kt,the controller executes the temperature compensated AF control to moveRR 104 to the in-focus position utilizing the function of the above AFdevice 16, thereby obtaining good image information.

The manual focusing devices 18′, 19′ may be any means that can detectthe operation such as on/off, without having to be limited to on/off ofswitch as described above.

The optical apparatus of the ninth embodiment shown in FIG. 14 and FIG.15 is constructed in the same structure as the optical apparatus of theseventh embodiment except for provision of the manual zooming devices20′, 21′ for zooming the variator lens 102 by manually driving the lensdrive unit 8 through the controller 7′.

In FIG. 14, numerals 20′, 21′ designate manual zooming switches. Witheither switch kept in the on state, the switch 20′ drives the variatorlens 102 to the telephoto end or the switch 19′ drives the variator lens102 to the wide angle end.

In the ninth embodiment, while the operation of the AF device 16 isstopped by the AF controller 17 and when the view angle is changed bythe zooming operation with the manual zooming switch 20′, 21′, thecontroller determines that the idle state for photography after idle isbroken, it stores the ambient temperature at the end of the zoomoperation by the manual zoom switch 20′, 21′, then it assumes that theidle state is again established thereafter, the controller makes thedetector 12 detect the ambient temperature in such an idle state tostore the ambient temperature detected, and it determines whether thetemperature change value ΔT of the difference between the latestdetected temperature obtained from the detector 12 after the ambienttemperature and the reference temperature is more than thepredetermined, specific value Kt as described previously. If thetemperature change value ΔT is not more than the predetermined, specificvalue Kt, the controller obtains the correction amount (temperaturecorrected position data) Prr from the previous relation and to move RR104 by the lens drive unit 9 so as to compensate for the variation inthe position of the image plane of the optical system due to the changeof ambient temperature. On the other hand, if the above temperaturechange value ΔT is more than the specific value Kt, the controller movesRR 104 to the in-focus position utilizing the function of the above AFunit 16, thereby correcting the variation in the position of the imageplane of the optical system due to the change of ambient temperature.

Specifically, while the operation of the AF device 16 is stopped by theAF controller 17′ and at the end of the zoom operation of the variatorlens 102 by the manual zooming device 20′, 21′, the controller 7 storesthe detected temperature obtained from the detector 12 and calculatesthe temperature change value ΔT of the difference between the latestdetected temperature obtained from the detector 12 after the previouslydetected temperature and the reference temperature and a determiningcircuit not shown determines whether the absolute value of thistemperature change value ΔT is more than the predetermined, specificvalue Kt. If the absolute value of the temperature change value ΔT isnot more than the predetermined, specific value Kt, the controllerobtains the correction amount (temperature corrected position data) Prrby the previous relation and moves RR 104 by the lens drive unit 9,thereby correcting the variation in the position of the image plane ofthe optical system due to the change of ambient temperature. On theother hand, if the absolute value of the temperature change value ΔT ismore than the specific value Kt, the above AF device 16 is functioned tocontrol the drive of the lens drive unit 9, based on the in-focus signalof the AF device 16, to move RR 104 to the in-focus position, therebycorrecting the variation in the position of the image plane of theoptical system due to the change of ambient temperature. This cancorrect the variation in the position of the image plane of the opticalsystem due to the change of ambient temperature, thereby obtaining goodimage information.

The operation of the ninth embodiment is next explained using theflowchart of FIG. 15. It is determined at step 1601′ whether the AFfunction of the AF device 16 is on or off. If it is on, the AF off flagis cleared at step 1602′ and then the flow returns to step 1601′. If theAF function is off, it is determined at step 1603′ whether the AF offflag is cleared. If cleared, a temperature detection value is read bythe detector 12 at step 1604′, the temperature detection value (detectedtemperature) is set as a detected temperature T1 in the MF (manualfocus) mode at step 1605′, and the AF off flag is set at step 1606′.

If at step 1603′ the AF off flag is not cleared, that is, if it is set,step 1607′ is carried out to determine whether the manual zooming switch20′ or 21′ is on or off. If either one is on, the zoom off flag iscleared at step 1608′ and then the flow returns to step 1601′. If theyare off, it is determined at step 1609′ whether the zoom off flag iscleared. If it is cleared, the zoom off flag is set at step 1610′, atemperature detection value is read at step 1604′, and the processesincluding step 1605′ and the subsequent steps are carried out.

If at step 1609′ the zoom off flag is not cleared, that is, if it isset, a temperature detection value is read at step 1611′ and it isdetermined at step 1612′ whether the temperature detection value(detected temperature) is equal to the previously detected temperatureT1. If they are equal, the flow returns to step 1601′. If they aredifferent, step 1613′ is carried out to obtain the temperature changevalue ΔT of the difference between the later detected temperatureobtained at step 1611′ and the reference temperature T0 and to determinewhether the absolute value thereof is more than the predetermined,specific value Kt. If the temperature change value ΔT is not more thanthe specific value Kt, step 1614′ is carried out to execute thetemperature compensated control to obtain the correction amount Prr fromthe previous relation and to move RR 104 so as to compensate for thevariation in the position of the image plane of the optical system. Onthe other hand, if at step 1613′ the absolute value of the temperaturechange value ΔT is more than the specific value Kt, step 1615′ iscarried out to execute the temperature compensated AF control to move RR104 to the in-focus position by the AF function. Then step 1616′ iscarried out to update the previously detected temperature T1 to thelater detected temperature. Then the flow returns to step 1601′.

As described above, the ninth embodiment is arranged in such a way thatwhile the operation of the AF device 16 is stopped by the AF controller17 and at the end of the zoom operation of the variator lens 102 by themanual zooming device 20′, 21′, if the temperature change value ΔT ofthe difference between the latest detected temperature obtained from thedetector 12 and the reference temperature is not more than thepredetermined, specific value Kt, the controller executes thetemperature compensated control to obtain the correction amount Prr ofRR 104 and to move RR 104 by the lens drive device 9 so as to correctthe variation in the position of the image plane of the optical systemand that, on the other hand, if the absolute value of the temperaturechange value ΔT is more than the specific value Kt, the controllerexecutes the temperature compensated AF control to move RR 104 to thein-focus position utilizing the function of the above AF device 16,thereby obtaining good image information.

The manual zooming devices 20′, 21′ may be any means that can detect theoperation such as on/off, without having to be limited to on/off ofswitch as described above.

As detailed above, since the optical apparatus of the present embodimentis constructed as described above, it can obtain good image informationwithout defocus even with occurrence of temperature changes duringzooming and during the operation of AF function or during stop of the AFfunction, or in the cases where the temperature is constant but deviatesfrom the reference temperature.

The optical apparatus of the present embodiment uses a single detector12, but it may be arranged to use plural detectors 12 for compensationfor variations in the position of the image plane of the optical system1, which enables higher-accuracy temperature compensated control.

The optical apparatus of the present embodiment was described as theexample where the environmental changes were the temperature changes,but in the cases where the environmental changes are humidity changes orpressure changes, the apparatus can handle such changes in the samemanner in the foregoing structure with provision of a detector thereof.For example, the apparatus may be arranged to have either a temperaturedetector or a humidity detector, or the apparatus may be arranged tohave the both detectors so as to correct defocus due to the temperaturechanges and humidity changes.

As explained above, since the above embodiments are arranged so thatduring photography with operation of the AF device using the opticalsystem (photographing lens) having the moving lens unit arranged to moveon the optical axis for focus or magnification change, when the AFfunction is stopped for some reason and, for example, if environmentalchanges such as temperature changes or humidity changes occur, the AFfunction is utilized to control the drive of the moving lens unit by thelens drive unit according to the environment changes, the apparatus cancorrect the deviation in the position of the image plane caused by theenvironmental change with high accuracy and can maintain high opticalperformance, thereby providing the optical apparatus suitable for videocameras, silver-salt cameras, electronic still cameras, and so on.

Since the optical apparatus is arranged so that during photography withoperation of the AF device using the optical system (photographing lens)having the moving lens unit arranged to move on the optical axis forfocus or magnification change, when the AF function is stopped for somereason and, for example, if an environmental change such as atemperature change or a humidity change occurs, the AF function isutilized to control the drive of the moving lens unit by the lens driveunit according to the environmental change, or movement of the movinglens unit is properly determined every time from control informationaccording to the environment change and the lens drive unit controls thedrive of the moving lens unit, based thereon, the apparatus can correctthe deviation in the position of the image plane caused by theenvironment change with high accuracy and can maintain high opticalperformance, thereby providing the optical apparatus suitable for videocameras, silver-salt cameras, electronic still cameras, and so on.

What is claimed is:
 1. An optical apparatus having an image-formingoptical system comprising a movable lens, said optical apparatuscomprising: a manual operation member for being manually operatedexternally and for outputting an operation signal in accordance with amanual operation thereof; a lens drive mechanism for moving said movablelens in accordance with the operation signal from said manual operationmember; a condition detecting device for detecting a temperature changeor a humidity change of said optical apparatus and for outputting astate detection signal; a determining device for determining whethersaid manual operation member outputs the operation signal; and a controldevice for setting, when said determining device determines that saidmanual operation member does not output the operation signal, acorrection amount of said movable lens in accordance with the statedetection signal and for actuating said lens drive mechanism so as tomove said movable lens for correction. wherein said control devicememorizes the state detection signal from said condition detectingdevice in a case that said determining device determines that saidmanual operation member does not output the operation signal, andcompares a memorized state detection signal with a current statedetection signal from said condition detecting device so as to set thecorrection amount of said movable lens in accordance with a signalvariation obtained by a comparison of the state detection signals.
 2. Anoptical apparatus according to claim 1, wherein said image-formingoptical system has a first lens for magnification change, and a secondlens, located behind said first lens and along the optical axis, forcorrecting a change of the imaging position upon focus action and uponmagnification change, said second lens corresponding to said movablelens.
 3. An optical apparatus according to claim 1, wherein said manualoperation member includes an operation member for performing a manualfocus operation.
 4. An optical apparatus according to claim 1, whereinsaid optical apparatus is a video camera and said movable lens of saidimage-forming optical system is a focus lens for adjusting the imagingposition.
 5. An optical apparatus according to claim 1, wherein saidimage-forming optical system comprises at least one plastic lens.
 6. Anoptical apparatus according to claim 5, wherein said image-formingoptical system has a first lens for magnification change, and a secondlens, located behind said first lens and along the optical axis, forcorrecting a change of the imaging position upon focus action and uponmagnification change, said second lens corresponding to said movablelens.
 7. An optical apparatus according to claim 5, wherein said controldevice comprises a memory device for storing data for correction of saidmovable lens, and wherein said control device retrieves specificcorrection data out of said memory device, based on the detection resultof said condition detecting device, and said lens drive mechanism movessaid movable lens by the specific correction data.
 8. An opticalapparatus according to claim 7, wherein the data for correction isdefined as a function of a difference between a detected value detectedby said condition detecting device and a reference value.
 9. An opticalapparatus according to claim 7, wherein the data for correction isdefined as a value obtained by multiplying the difference between adetected value detected by said condition detecting device and areference value by correction coefficient data and adding position dataof said movable lens to a result of the multiplication.
 10. An opticalapparatus according to claim 7, wherein said condition detecting devicecomprises a sensor using a thermally sensitive resistor.
 11. An opticalapparatus according to claim 7, wherein said condition detecting devicecomprises a sensor using a thermistor.
 12. An optical apparatusaccording to claim 7, wherein said condition detecting device comprisesan electrostatic capacity type sensor.
 13. An optical apparatus havingan image-forming optical system comprising a movable lens, said opticalapparatus comprising: a manual operation member for being manuallyoperated externally and for outputting an operation signal in accordancewith a manual operation thereof; a lens drive mechanism for moving saidmovable lens in accordance with the operation signal from said manualoperation member; a focus adjusting device for allowing an auto focusfunction so as to automatically adjust an imaging position by movingsaid movable lens on the basis of a detection result of a focusdetection device; a condition detecting device for detecting atemperature change or a humidity change of said optical apparatus, andoutputting a state detection signal; a determining device fordetermining whether said manual operation member outputs the operationsignal, and for determining whether the auto focus function of saidfocus adjusting device is operated; and a control device for setting,when said determining device determines that said manual operationmember does not output the operation signal and determines that the autofocus function of said focus adjusting device is not operated, acorrection amount of said movable lens in accordance with the statedetection signal so as to drive said lens drive mechanism to move saidmovable lens for correction.